Virginia Open File Report 2011-7 Department of Geologic Map of the Providence Forge Quadrangle, Virginia Mines, Minerals Virginia Division of Geology and Mineral Resources and Energy GEOLOGIC MAP OF THE PROVIDENCE FORGE QUADRANGLE, VIRGINIA (QUINTON) AMY K. GILMER AND C. R. BERQUIST, JR. 2011 77° 07’ 30’’ Qal (TUNSTALL) Te 77° 00’ (NEW KENT) 37° 30’ 37° 30’ Tbc Tbc Ty 2010090-2 DESCRIPTION OF MAP UNITS CORRELATION OF MAP UNITS Tbc 2010112-2 2010091-1 Ts Ty A Ty 2009323-1 Ts Tbc Ty Te Ts Ts SURFICIAL UNITS Te ml Ty Qal 2009323-2 Qal SURFICIAL UNITS Te Tbc 2009240-1 Modified Land – Extensive cut and/or fill related to grading, excavation, and ml Ty Tbc Tbc Qsh Ty mining-related activities, predominantly areas dredged for sand and gravel Ts Qal ml ml Ty Te Te extraction. Modified land along roads is not shown, except along overpasses and Tbc Ts Ts Tbc Tbc Ts and rest areas. Holocene. Variable thickness. Ty Ts Tbc Ty Ty Tbc F-1-1 Qal Ty Qsh Qal Alluvium – Floodplain deposits consisting of pebbly sand, sand, and silt, with Te PLEISTOCENE Qal HOLOCENE TO 2010105-1 interbeds of silt and fine sand. Organic matter is common; includes swamp and E-1-2 ml Ty marsh environments. Holocene to Pleistocene. Variable thickness. COASTAL PLAIN Qal Ty Ts UNITS Qsh Ty COASTAL PLAIN UNITS 2010007-1 Tbc Ty Ty Qtlp Ty Ty Tabb Alloformation, Lynnhaven/Poquoson Members – Silty, fine- to Qtlp Unconformity Qal Qal medium-grained sand grading downward to pebbly sand with heavy minerals Ts Ts Tbc Ty Ts Tbc common and interbeds of peat and organic mud; surface elevations below 18 Ty Tbc Qcc feet. Qts Tbc B-2-1 Ty U D Ty Unconformity Tabb Alloformation, Sedgefield Member – Clayey, fine-grained sand grading Tbc Qsh Qts Ty downward to pebbly sand with heavy minerals common; interbeds of peat and Tbc Ty Qcc I-3-1 Qsh B2294 Ty organic mud common. Thin deposits of the Tabb Alloformation might be found QUATERNARY Ty Te B2295 B2297 Te Qcc on broad land surfaces at elevations of less than 28 feet resulting from 2010105-3 B2296 Te Ty Unconformity Figure 1. Fluvial channel deposit in the Shirley Formation overlying fine- to Ty reworking of Shirley sediments. Allostratigraphic classification was proposed Ty Ty medium-grained sand of the Yorktown Formation near Stony Run. Shovel for scale. Ts Ty by Doar and Berquist (2009). A-3-1 Qc B2298 Qal PLEISTOCENE Te B2299 B2301 Ts Qal Ts B2302 Qsh Ts Shirley Alloformation – Gray to brown gravel, sand, silt and clay; occurs above Unconformity Ty B2300 Qsh Qsh Qcc younger alluvial deposits on flats adjacent to Chickahominy River at elevations 2009309-1 Tbc Ty B2303 2009342-2 B2304 ranging up to 48 feet above present sea level. Quartzite clasts with the trace fossil CENOZOIC Qcc 2009295-1 Tbc Te Skolithos are common. Thickness is typically up to 50 feet (15.2 meters), but Qts Unconformity Ts Ty Qsh Tbc could be greater in paleochannels. The type section was defined by Johnson and Berquist (1989). Allostratigraphic classification was proposed by Doar and 2010095-2 Ty Qsh 2009243-2 Qw Te Ty Berquist (2009). Tc Tbc Te Te Unconformity 2010095-3 Chuckatuck Alloformation – Light- to medium-gray, yellowish-orange and Tbc Te Ty Qc 2009239-1 Ty reddish-brown sand, silt, and clay with minor amounts of dark-brown and Ts Ty Tbc Tbc Qal Tbc brownish-black peat. Sediments were deposited during a marine transgression Ty Ty Te where sea level reached a maximum elevation of approximately 58 above present Te Tbc Unconformity Te 2009342-1 Ts Tbc sea level. Morphologic expression of terraces resulting from this event is Ty 2010061-1 Qal Ty consistent across the Virginia Coastal Plain where the toe of the scarp cut into Qsh Ts 2010112-1 Ty adjacent highlands is about 58 feet, and terrace surface (flat) ranges from about 40 Qts Te Ty Qcc PLIOCENE Qts to 55 feet. This morphology is found adjacent to today’s major estuaries, as well Ty Qal Unconformity Ty as smaller tributaries like the Chickahominy River. Fluvial-estuarine facies Qcc Te B2305 NEOGENE Ty Qsh includes, from bottom to top, (1) channel-fill deposits of poorly sorted, Ty Qts cross-bedded, pebbly and cobbly sand interbedded, locally, with peat and sandy 90419AA Ty Te silt rich in organic matter, (2) moderately well-sorted, cross-bedded to planar Unconformity Tc FAULT FORGE ROVIDENCE Qts Qcc P bedded, fine- to medium-grained sand grading up ward into (3) clayey silt and Te 2010120-2 Qsh Ty Ts sandy and silty clay. Thickness is up to 26 feet (7.9 meters) but could be greater Qal Qcc Te Figure 2. Shell fossil “ghosts” in the sands of the Yorktown Formation. Qts Te Ty Tbc in paleochannels. The type section was defined by Johnson and Berquist (1989). Unconformity Qsh 2010120-1 Qcc Qsh Tbc Charles City Alloformation – Medium to light gray, silty fine sand with Qsh Qc Qsh Qcc Qcc MIOCENE Qts Tc 2009295-2 scattered rounded quartz and quartzite pebbles, cobbles, and boulders; quartzite Te Qsh Qcc Ts Ty Ts Ty Tbc clasts with the trace fossil Skolithos are common. Sediments were deposited Qal Ty during a marine transgression where sea level reached a maximum elevation of Qsh Qal Tc sg-501 approximately 78 above present sea level. Morphologic expression of terraces Qts ml 2009295-3 resulting from this event is consistent across the Virginia Coastal Plain where the SOURCES Qsh 2009239-2 Qal toe of the scarp cut into adjacent highlands is about 78 feet, and terrace surface Qts Qsh Coch, N. K., 1965, Post-Miocene stratigraphy and morphology, inner coastal Te 2009310-3 Ty Qal (flat) ranges from about 55 to 70 feet. This morphology is found adjacent to Ty Qts 08177AD Qts today’s major estuaries, as well as smaller tributaries like the Chickahominy plain, southeastern Virginia: Office of Naval Research, Geography Branch Qsh Qal 2009324-1 Tc 2009296-3 2009310-2 River and Rumley Marsh. The typical succession of sediments fines upwards Technical Report, no. 6, 97 p. Qts Qsh Te 2010047-1 from coarse-grained sand and pebbles to clayey fine-grained sand and clay. Coch, N. K., 1968, Geology of the Benns Church, Smithfield, Windsor and Qsh Chuckatuck quadrangles, Virginia: Virginia Divsion of Mineral Resources Qsh Qts 2009296-4 Furthermore, soil survey maps show clay-rich sediments underlie these terrace Ty Tbc Report of Investigations 17, 39 p. Tc Qal Qts 2010029-3 Ty remnants instead of typically sandy sediments of the Yorktown Formation. The Qsh Costain, J. K., L. Glover, III, and A. K. Sinha, eds.,1979, Evaluation and targeting Ts Te Qal type section was defined by Johnson and Berquist (1989). Thickness is up to 40 B3320 of geothermal energy resources in the southeastern United States: Series of 2010095-1 Ts feet (12.2 meters) but could be greater in paleochannels. Allostratigraphic Tbc Qtlp ml Progress Reports VPI&SU-5103, and VPI&SU-5648. Qcc classification was proposed by Doar and Berquist (2009). Tbc Qtlp Doar, W. R.,III., and Berquist, C. R., Jr,. 2009, The Late Pliocene and Pleistocene Qts Qts sg-504 Qal 2008008-3 Windsor Alloformation – Gray and yellowish- to reddish-brown sand, gravel, marine stratigraphies of South Carolina and Southeastern Virginia (abs.): B3310 Ts Tc Qts ml Qsh B3319 Qw Geological Society of America Abstracts with Programs, v. 41, No. 1, p. 53. B3309 Qal Ty silt, and clay. Occurs on flats at elevations of 60 to 95 feet above present sea level. Ty Tc ml ml Qts Johnson, G. H., and Berquist, C. R., Jr., 1989, Geology and mineral resources of (WALKERS) (ROXBURY) B3311 Ty B3314 Fluvial-estuarine deposits consist of muddy, coarse, trough cross-bedded sand B3312 B3313 sg-503 Qtlp Qts the Brandon and Norge quadrangles: Virginia Division of Mineral Te Te B3315 and gravel grading upward to sandy silt and clay. Thickness is up to 48 feet (14.6 B3317 Resources Publication 87, 28 p. Qtlp B3316 B3318 meters), but could be greater in paleochannels. The type section was defined by Mixon, R.B., and Newell, W.L., 1977, Stafford fault system: Structures ml Qal Ty Ty Coch (1968) and later amended by Johnson and Berquist (1989). Qts Te Ts Qtlp 2009240-2 documenting Cretaceous and Tertiary deformation along the Fall Line in Northeastern Virginia: Geology, v. 5, p. 437-440. Qtlp Qsh Bacons Castle Formation – Gray, red and reddish-brown, fine grained sandy Figure 3. Turritella sp. in the Claremont Manor member of the Eastover Formation Tbc clay and clayey silt commonly exhibiting lenticular bedding; typically found at Mixon, R.B., and Newell, W.L., 1978, The faulted Coastal Plain margin at near Stony Run. Pencil for scale. Tbc 2009310-1 Qts Qal highest elevations in the map area; ranges in thickness up to 20 feet (6.1 meters); Fredericksburg, Virginia: Guidebook for the Tenth Annual Virginia Ts Qal sg-505 2009294-2 commonly overlies reddish-brown to brownish-yellow quartzofeldspathic sands Geological Field Conference, Reston, Virginia, 50 p. 2009297-1 Qsh Qtlp and pebble to cobble sized gravel, with and without clay. The unit ranges in Mixon, R.B., and Newell, W.L., 1982, Mesozoic and Cenozoic compressional Ty Qal Qal faulting along the Atlantic Coastal Plain margin, Virginia, in Lyttle, P.T., Ty ml 2009294-3 elevation from 85 to 140 feet above present sea level. Proposed by Coch (1965) Tbc Qts Ts and formally named by Coch (1968) and informally subdivided into the Central Appalachian geology: Northeast-Southeast Geological Society of Ty Qts America 1982 Field Trip Guidebooks, p.